CN111129311A

CN111129311A - Flexible organic photomultiplier detector based on ultrathin silver film anode and fabrication method

Info

Publication number: CN111129311A
Application number: CN201911334247.6A
Authority: CN
Inventors: 石林林; 张叶; 崔艳霞; 王文艳; 冀婷; 李国辉; 梁强兵; 郝玉英; 吴玉程
Original assignee: Taiyuan University of Technology
Current assignee: Taiyuan University of Technology
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2020-05-08

Abstract

The invention relates to the field of fabrication of organic photomultiplier detectors. A flexible organic photomultiplier detector based on an ultra-thin silver film anode comprises an anode layer, an anode modification layer, an active layer and a cathode layer. The anode layer is made of molybdenum trioxide, an ultra-thin The metal transparent electrode composed of silver film, the anode modification layer is molybdenum trioxide, the active layer is poly-3-hexylthiophene: phenyl-C ₇₀ -methyl butyrate, the cathode layer is aluminum, and the substrate used for the anode layer is a ZEOCOAT-treated polyethylene terephthalate PET with a thickness of 0.1-0.15mm, an all-olefin polymer. The invention also relates to a manufacturing method of the flexible organic photomultiplier detector based on the ultra-thin silver film anode.

Description

Flexible organic photomultiplier detector based on ultrathin silver film anode and manufacturing method

Technical Field

The invention relates to the field of manufacturing of organic photomultiplier detectors, in particular to a flexible organic photomultiplier detector which takes a metal transparent electrode formed by an ultrathin silver film with a wetting layer introduced on a flexible PET substrate as an anode and a manufacturing method thereof.

Background

Compared with inorganic photomultiplier detectors, photomultiplier detectors made of organic polymer materials have the advantages of light weight, low cost, wide material sources, environmental friendliness, flexibility and the like, and are paid much attention to. Most of the currently researched organic photomultiplier detectors are based on a glass rigid substrate, and the organic photomultiplier detectors are used as one of key components of intelligent flexible devices, so that the application of the organic photomultiplier detectors in certain flexible specific scenes is limited to a certain extent. Therefore, in order to achieve better flexibility, it is currently the most crucial task to find a transparent conductive anode that can be fabricated on a flexible substrate, has higher transmittance, is environmentally friendly, and can be fabricated in a large area with good mechanical flexibility.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: a transparent conductive material which has higher transmissivity, is green and environment-friendly, can be prepared in a large area and has good mechanical ductility is searched for as an anode on a flexible substrate, so that a high-performance and flexible organic photomultiplier is realized.

The technical scheme adopted by the invention is as follows: the utility model provides a flexible organic photomultiplier detector based on ultra-thin silver membrane positive pole, includes anode layer, positive pole modification layer, active layer, cathode layer, its characterized in that: the anode layer is molybdenum trioxide MoO with the thickness of 1 +/-0.2 nanometers₃A metal transparent electrode consisting of an ultrathin silver film of 9 +/-0.2 nanometers, wherein the anode modification layer is molybdenum trioxide MoO with the thickness of 4 +/-0.2 nanometers₃The active layer is poly-3-hexylthiophene with a thickness of 214 +/-0.2 nm, phenyl-C₇₀-butyric acid methyl ester (P3HT: PC₇₀BM) (Poly(3-hexylthiophene:[6,6]-phenyl-C₇₀-butyl-acid-methyl-ester), the cathode layer is aluminum with a thickness of 100 ± 0.2 nm, and the anode layer uses a substrate of polyethylene terephthalate PET with a thickness of 0.1-0.15mm treated with a cross-linked olefin polymer ZEOCOAT.

A method for preparing a flexible organic photomultiplier detector based on an ultrathin silver film anode comprises the following steps:

step one, preparing an active layer solution, namely respectively preparing 40 units of milligram of P3HT and PC₇₀BM are respectively dissolved in 1 unit ml of o-dichlorobenzene DCB and stirred evenly at 60 ℃, and prepared PC is taken₇₀Mixing BM solution and prepared P3HT solution according to the volume percentage of 1:100, and stirring uniformly at 60 ℃ to obtain the mass ratio P3HT: PC₇₀An active layer solution with BM of 100: 1;

step two, removing the protective film of the polyethylene terephthalate PET, using a cross-linked olefin polymer ZEOCOAT to improve the roughness of the surface of the PET as a substrate, and sequentially thermally evaporating MoO with the thickness of 1 +/-0.2 nanometers on the polyethylene terephthalate PET substrate₃A transparent electrode composed of an ultrathin silver film with a thickness of 9 +/-0.2 nm and used as an anode layer, and MoO with a thickness of 4 +/-0.2 nm formed by thermal evaporation₃As an anode modification layer, spin-coating an active layer solution on the anode modification layer to form P3HT: PC with a thickness of 214 + -0.2 nm₇₀The BM layer is used as an active layer, and aluminum with the thickness of 100 +/-0.2 nanometers is thermally evaporated on the active layer to be used as a cathode layer.

The anode layer is prepared by vacuum thermal deposition, wherein MoO with thickness of 1 + -0.2 nm₃The film is heated by a beam source furnace, the growth rate is maintained at 0.01-0.02 nm/s, the ultra-thin silver film with the thickness of 9 +/-0.2 nm is heated by a tantalum boat, and the growth rate is maintained at 0.7 nm/s.

In the second step, the preparation process of the anode buffer layer is vacuum thermal deposition, and MoO with the thickness of 4 +/-0.2 nanometers₃Heating the film by a beam source furnace, maintaining the growth rate at 0.01-0.02 nm/s, and standing for at least 5min, then in MoO₃The layer is spin coated with an active layer solution.

And spin-coating an active layer solution on the anode modification layer at the rotation speed of 1200 rpm, directly placing on a heating table after the spin-coating is finished, annealing at the temperature of 80 ℃ for 20 s, standing in a glove box for more than 3 min, and then, evaporating and plating cathode layer aluminum on the active layer.

The invention has the beneficial effects that: the invention improves the flexibility of the device and realizes the conversion from rigidity to flexibility of the device. The flexible organic photomultiplier detector is characterized in that an ultrathin metal silver film which is high in transmittance, green, environment-friendly, capable of being prepared in a large area and good in mechanical ductility is used as an anode on a flexible substrate, and the flexible organic photomultiplier detector is realized on the premise that the detector has excellent bright and dark current density, external quantum efficiency EQE and response rate R.

The flexible organic photomultiplier detector based on the ultrathin silver film anode has the dark current density of 0.60 mA/cm under the bias of-15V²The bright current density is 13.07 mA/cm²And the external quantum efficiency EQE is 80684.02%, the response rate is 242.29A/W, and compared with a glass rigid substrate organic photomultiplier detector, the flexible organic photomultiplier detector is realized on the premise of basically keeping the better performance of the detector.

The ultrathin noble metal film can effectively realize the preparation of flexible devices due to the advantages of higher light transmittance, excellent mechanical ductility and the like. Silver is most widely studied in the field of metal transparent electrodes because of its high conductivity. For example, ultra-thin silver films with a thickness of less than 10 nm are widely used as transparent electrodes in thin film solar cells. Besides serving as an electrode, the ultrathin silver film has the function of trapping light, and is beneficial to obtaining higher power conversion efficiency. And considering the problem of poor wettability of silver on some substrates, we treated the PET substrate with a cross-linked olefin polymer ZEOCOAT while introducing a metal oxide MoO with a thickness of 1 + -0.2 nm₃On one hand, the silver-doped silicon nitride film is used as an infiltration layer to induce silver to form a film and can play a role in increasing the transmission, and the silver-doped silicon nitride film is applied to an organic photomultiplier detector and utilizes the electron trap in an active layer to assist the hole tunneling function of an external circuit to realize a baseA flexible organic photomultiplier detector for an ultrathin silver film anode.

Drawings

FIG. 1: the dark state current density-voltage characteristic curve of the invention;

FIG. 2: the external quantum efficiency curve of the invention;

FIG. 3: the response rate curve of the invention;

FIG. 4: the invention relates to a flexible performance test curve of a flexible device.

Detailed Description

The materials used in the present invention are; [ Poly (3-hexylthiophenene-2, 5-diyl)](P3HT),[6,6]-phenyl-C₇₀-butyric-acid-methyl-ester](PC₇₀BM), molybdenum trioxide (MoO)₃) Silver, cross-linked olefin polymer (ZEOCOAT), bright cleaning milk (components are surfactant, calcium carbonate, organic acid and essence), Libai detergent (components are softened water, surfactant, vitamin E ester and lemon essence), deionized water, acetone and isopropanol. The combined dosage is as follows:

P3HT：40 mg ± 1 mg

PC₇₀BM： 40 mg ± 1 mg

MoO₃： 1 g ± 0.01 g

silver: 10 g. + -. 0.01 g

Crosslinked olefin polymer (ZEOCOAT): 30 μ L of

light cleansing milk: 1. + -. 0.5 mL

Liquid detergent: 2. + -. 0.5 mL

Deionized water: h₂O 8000 mL ± 50 mL

Acetone: CH (CH)₃COCH₃250 mL± 5 mL

Glass sheet: 19 mm. times.19 mm. times.1 mm

Polyethylene terephthalate (PET): 19 mm x 0.2 mm,

The organic polymer photomultiplier detector device has a four-layer structure and consists of an anode layer, an anode modification layer, an active layer and a cathode layer; the anode layer is MoO with a thickness of 1 + -0.2 nm₃And an ultra-thin silver film with a thickness of 9 +/-0.2 nanometersA metallic transparent electrode composed of a substrate layer prepared on a polyethylene terephthalate PET substrate spin-coated with a crosslinked olefin polymer ZEOCOAT. An anode modifying layer, i.e. 4 +/-0.2 nm of MoO, is arranged above the anode layer₃Layer, an active layer (P3HT: PC) is arranged above the anode modification layer₇₀And a cathode layer, namely an aluminum film, is arranged above the active layer of the BM. The preparation method comprises the following steps:

(1) selecting chemicals

The chemical material required by preparation is selected, and the quality, purity, concentration, fineness and precision are controlled as follows:

p3HT: solid powder with molecular weight of 3-6.5 ten thousand

PC₇₀BM: solid powder with particle size not more than 28 μm and purity 99.99%

MoO₃: solid powder with particle size not more than 28 μm and purity 99.99%

Silver: solid particles with specification of 2 x 5mm and purity of 99.99 percent

Deionized water: liquid with purity of 99.99 percent

Acetone: liquid with purity of 99.5%

Glass substrate: solid, 19 mm. times.19 mm. times.1 mm

A PET substrate: solid, 19 mm. times.19 mm. times.0.2 mm

(2) Preparation of active layer solution

1) 40 mg of P3HT and 40 mg of PC were weighed out respectively₇₀BM was placed in two 5 mL brown reagent bottles.

2) Respectively weighing 1 mL of DCB (o-dichlorobenzene) and placing the DCB into the two brown reagent bottles;

3) the solution was placed on a magnetic stirrer and stirred at 60 ℃ for at least 12 h.

4) Stirring well, taking 10 mu L of prepared PC₇₀BM solution was mixed with 1L of the prepared P3HT solution and then stirred uniformly at 60 ℃. The mass ratio of 100:1(P3 HT: PC) was obtained₇₀BM) active layer solution

(4) Cleaning of glass sheet and PET

1) Putting the glass sheet into a mixed solution of bright cleaning milk and detergent, and carrying out ultrasonic treatment for 1 h;

2) repeatedly rubbing the front and back sides of the glass sheet with disposable gloves until the front and back sides are washed by deionized water to form water films;

3) placing the glass sheet in an ultrasonic cleaner, adding deionized water, and ultrasonically cleaning for 15 min;

4) placing the glass sheet in an ultrasonic cleaner, adding acetone, and ultrasonically cleaning for 15 min;

5) placing the glass sheet in an ultrasonic cleaner, adding isopropanol, and ultrasonically cleaning for 15 min;

6) and (4) placing the washed glass sheet in a plasma cleaning machine for ozone cleaning for 5 min.

The protective film was removed from the PET substrate, and the adhered dust was blown off, and the crosslinked olefin polymer ZEOCOAT was spin-coated on a clean PET substrate at a rate of 2000rpm for 30 seconds for use, with a PET thickness of 0.1mm to 0.15 mm.

(5) Vacuum evaporation, form conversion, vapor deposition, film growth, preparation of silver transparent electrode and anode buffer layer

① the preparation is carried out in a vacuum evaporation furnace;

② Place glass sheets and PET substrate

Opening the vacuum evaporation furnace, and respectively fixing the glass sheet and the PET substrate on a turntable at the top of the furnace chamber;

③ placing evaporation materials in evaporation container respectively

And (3) coating the evaporation material: putting the molybdenum trioxide chemical substance powder in an evaporation crucible at the bottom of a furnace chamber according to the quantity, and putting the silver particles in a tantalum boat according to the quantity;

④ adjusting a quartz thickness measuring probe and a quartz monitoring probe on the furnace wall to make the quartz thickness measuring probe aim at the substrate on the turntable and make the two quartz monitoring probes aim at molybdenum trioxide and silver respectively;

⑤ closing the door of the vacuum evaporation furnace and sealing;

⑥ starting a mechanical vacuum pump and a molecular vacuum pump, and extracting air in the furnace cavity to make the vacuum degree in the furnace less than or equal to 0.0005 Pa and keep constant;

⑦ turning on the turntable, rotating the conductive glass with the turntable at 8 r/min;

⑧ opening the quartz thickness measuring probe;

⑨ evaporating transparent electrode and its anode modifying layer:

1) starting a crucible power supply containing molybdenum trioxide to sublimate molybdenum trioxide powder from a solid state to a gas state, depositing and growing gaseous molecules on a substrate to form a planar film layer, adjusting a crucible power supply control button, raising the temperature to maintain the film growth rate at 0.01-0.02 nm/s, and keeping the film layer thickness at 1 +/-0.2 nm;

2) starting a spiral tungsten filament power supply filled with silver to sublimate the silver from a solid state to a gas state, depositing and growing gas molecules on the molybdenum trioxide infiltration layer to form a planar film layer, adjusting a tungsten boat power supply control knob, increasing current, and maintaining the film growth rate at 0.7nm/s and the film layer thickness at 9 nm +/-0.2 nm;

3) starting the crucible power supply containing molybdenum trioxide again to ensure that the molybdenum trioxide powder is sublimated from a solid state to a gaseous state, gaseous molecules are deposited and grown on the substrate to form a planar film layer, adjusting the crucible power supply control button, raising the temperature to ensure that the growth rate of the film is maintained at 0.01-0.02 nm/s, and the thickness of the film layer is 4 +/-0.2 nanometers;

in the preparation process, a quartz thickness measuring probe measures the evaporation thickness, and the thickness value is displayed by a display screen;

in the preparation process, the evaporation process and the evaporation condition are observed through a middle observation window;

in the preparation process, the evaporation material is heated to sublimate, the form is converted, and vapor deposition is carried out on the substrate to generate a planar film layer;

⑩ standing and cooling in vacuum state

After the film layer is evaporated, standing and cooling the substrate plated with the transparent electrode in a vacuum furnace for 10 min;

(6) spin coating of active layer

1) Transferring the substrate coated with the silver transparent electrode and the anode buffer layer into a glove box, standing for at least 5 min, and taking 25 μ LP3HT: PC₇₀Dropping BM mixed solution into the vapor deposition MoO₃At the surface of the anode buffer layer at the rotating speed of 1200 r/minSpin coating for 30 s;

2) spin-coated P3HT: PC₇₀And (3) placing the metal transparent electrode substrate of the BM on a heating table, annealing at 80 ℃ for 20 s, and then continuously filling the BM into a pot after standing in vacuum for 15 min. .

(7) Vacuum evaporation, form conversion, vapor deposition, film growth and preparation of aluminum cathode

① the preparation is carried out in a vacuum evaporation furnace;

② placing the mixture with P3HT PC₇₀Metal transparent electrode substrate of BM

Opening the vacuum evaporation furnace, rotating P3HT: PC₇₀The metal transparent electrode substrate of BM is fixed on the turntable on the top of the furnace chamber and is screwed with P3HT: PC₇₀The metal transparent electrode substrate of the BM faces downwards;

③ placing evaporation material in evaporation container

Putting the evaporation material aluminum wire into a tungsten boat according to the quantity;

④ adjusting the quartz thickness measuring probe and the quartz monitoring probe on the furnace wall to make the quartz thickness measuring probe align with the substrate on the turntable and the quartz monitoring probe align with the aluminum;

⑤ closing the door of the vacuum evaporation furnace and sealing;

⑧ opening the quartz thickness measuring probe;

⑨ aluminum-vapor-deposited cathode:

turning on a spiral tungsten filament power supply filled with aluminum to sublimate the aluminum from a solid state to a gas state, depositing and growing gas molecules on the active layer to form a planar film layer, adjusting a tungsten boat power supply control knob, increasing current, and maintaining the growth rate of the film at 0.1 nm/s and the thickness of the film layer at 100 +/-0.2 nm;

during the preparation process, the evaporation material is heated to sublimate, and the form is converted, wherein P3HT PC is rotated₇₀Carrying out vapor deposition on the metal transparent electrode substrate surface of the BM to generate a planar film layer;

⑩ standing and cooling in vacuum state

After the film layer is evaporated, the organic photomultiplier is stood and cooled for 10 min in a vacuum furnace;

⑪ collecting product organic polymer photomultiplier

Closing the molecular vacuum pump and the mechanical vacuum pump;

opening an air inlet valve;

opening a door of the evaporation cabin;

and taking out the flexible organic photomultiplier detector with the anode being the ultrathin metal silver film.

(7) Detection, analysis, characterization

Detecting, analyzing and characterizing the performance of the prepared organic polymer photomultiplier;

measuring a current density-voltage curve of the device by using a Keithley 2400 digital source meter; the method comprises the following steps of measuring the external quantum efficiency EQE and the response rate R of the organic photomultiplier detector by using a Zolix Omni-lambda 300 Monochromyator/Spectrography and a dark box; the bending performance of the organic photomultiplier detector is tested by a flexible displacement table device. And (3) performing comparative analysis on the performances of devices prepared on a glass rigid substrate and a PET flexible substrate respectively by using the ultrathin metal silver film as an anode.

And (4) conclusion: the device with the rigid glass substrate is called a traditional organic photomultiplier detector, and the device with the flexible PET substrate is called a flexible organic photomultiplier detector. From the dark state current density-voltage characteristic curve (fig. 1), it is seen that the dark current of the flexible organic polymer photomultiplier is lower than that of the traditional organic photomultiplier, mainly because the ultrathin silver film electrode prepared on the flexible substrate has higher surface resistance, and the ability of the electrode to collect carriers is effectively hindered in the dark state.

The preparation of devices on different substrates, i.e. GLASS/MoO, was analyzed₃/ Ag / MoO₃/ P3HT:PC₇₀BM/Al and PET/MoO₃/Ag / MoO₃/ P3HT:PC₇₀The external quantum efficiency EQE, the response rate R and the EQE performance change of BM/Al in the bright state for different times of bending are shown in fig. 2, 3 and 4. From the figure, the EQE and R performances of the ultra-thin metal silver film as an anode on the PET flexible substrate device are comparable to those of the glass rigid substrate device, but slightly lower than those of the glass rigid substrate device, mainly because the light transmittance of the ultra-thin metal silver film electrode on the PET flexible substrate is lower than that of the glass rigid substrate. However, from the flexible bending curve, the flexible organic photomultiplier according to the present invention has good flexibility, in which the EQE remains 85.19% after being bent 10 times, and the EQE remains 65.81% after being bent 1000 times.

Compared with the background art, the invention has obvious advancement. A transparent anode which is made of an ultrathin noble metal silver film which is 9 nm, has high transmittance and excellent mechanical ductility, is green and environment-friendly and can be prepared in a large area is prepared on a flexible PET substrate to serve as an anode of a device, the defect that the traditional device cannot realize flexibility by taking rigid glass as the substrate is ingeniously overcome, the flexibility of an organic photomultiplier detector is realized, the application range of the device is expanded, and an anode modification layer MoO is prepared on a substrate by a vacuum thermal deposition method₃The active layer P3HT PC is prepared by spin coating₇₀BM, the method is simple and convenient, the cost is low, and a flexible organic photomultiplier detector with excellent performance can be obtained, so that the BM has potential application value.

Claims

1. a flexible organic photomultiplier detector based on ultra-thin silver film anode, comprising anode layer, anode modification layer, active layer, cathode layer, it is characterized in that: anode layer is the molybdenum trioxide MoO that thickness is 1 ± 0.2 nanometers A metal transparent electrode composed of ultra-thin silver films of ₃ and 9 ± 0.2 nanometers, the anode modification layer is molybdenum trioxide MoO ₃ with a thickness of 4 ± 0.2 nanometers, and the active layer is poly-3-hexylthiophene with a thickness of 214 ± 0.2 nanometers: Phenyl-C ₇₀ -methyl butyrate P3HT: PC ₇₀ BM, the cathode layer is aluminum with a thickness of 100 ± 0.2 nm, the anode layer uses a substrate treated with a cross-linked olefin polymer ZEOCOAT with a thickness of 0.1-0.15 mm of polyethylene terephthalate PET.

2. the method for making a kind of flexible organic photomultiplier detector based on ultra-thin silver film anode according to claim 1 is characterized in that carrying out according to the following steps:

Step 1: Prepare the active layer solution. Dissolve 40 units of mg of P3HT and PC ₇₀ BM in 1 unit of milliliter of o-dichlorobenzene DCB and stir them evenly at 60°C. Take the prepared PC ₇₀ BM solution and the prepared The P3HT solution was mixed according to the volume percentage of 1:100 and then stirred evenly at 60 °C to obtain an active layer solution with a mass ratio of P3HT:PC ₇₀ BM of 100:1;

Step 2. After the polyethylene terephthalate PET is peeled off the protective film, the surface is treated with cross-linked olefin polymer ZEOCOAT to improve the roughness as a substrate, and the polyethylene terephthalate PET is lined with MoO ₃ with a thickness of 1 ± 0.2 nanometers and an ultra-thin silver film with a thickness of 9 ± 0.2 nanometers are sequentially thermally evaporated on the bottom to form a transparent electrode as an anode layer, and MoO ₃ with a thickness of 4 ± 0.2 nanometers is thermally evaporated as an anode modification layer. The active layer solution was spin-coated on the anode modification layer to form a P3HT:PC ₇₀ BM layer with a thickness of 214 ± 0.2 nm as the active layer, and aluminum with a thickness of 100 ± 0.2 nm was thermally evaporated on the active layer as the cathode layer.

3. the method for making a kind of flexible organic photomultiplier detector based on ultra-thin silver film anode according to claim 2, is characterized in that: the preparation technique of anode layer is vacuum thermal deposition, and wherein thickness is 1 ± 0.2 nanometers. The MoO ₃ film was heated by a beam source furnace, and the growth rate was maintained at 0.01 - 0.02 nm/s, and the ultra-thin silver film of 9 ± 0.2 nm was heated by a tantalum boat, and the growth rate was maintained at 0.7 nm/s.

4. the method for making a kind of flexible organic photomultiplier detector based on ultra-thin silver film anode according to claim 2, is characterized in that: in step 2, anode buffer layer preparation technology is vacuum thermal deposition, and thickness is 4± _The 0.2 nm MoO3 film was heated by a beam source furnace, the growth rate was maintained at 0.01 - 0.02 nm/s, and then left for at least 5 min, and then the active layer solution was spin _- coated on the MoO3 layer.

5. The method of claim 1 for making a flexible organic photomultiplier detector based on an ultra-thin silver film anode according to claim 2, characterized in that: on the anode modification layer, spin coating activity at a rotating speed of 1200 rpm After spin coating, it was directly placed on the heating table, annealed at 80 °C for 20 s, and then left for more than 3 min in the glove box, and then the cathode layer aluminum was evaporated on the active layer.